Method and apparatus for etching coated substrates

Abstract

A method for etching substrates, comprising providing at least a first and a second substrate having a coating selected from the group consisting of semiconductor coatings, metallic coatings, and mixtures thereof and introducing at least the first substrate and an etchant into a first tank to etch at least a portion of the coating from the first substrate, introducing at least the second substrate into a second tank and transferring the etchant from the first tank to the second tank to provide etch of at least a portion of the coatings from the second substrate, and removing the etched first substrate from the first tank.

What is claimed is:  
     
       1. A method for etching substrates, the method comprising: 
       providing at least a first and a second substrate having a coating selected from the group consisting of semiconductor coatings, metallic coatings, and mixtures thereof,  
       introducing at least the first substrate and an etchant into a first tank to etch at least a portion of the coating from the first substrate;  
       introducing at least the second substrate into a second tank;  
       transferring the etchant from the first tank to the second tank to etch at least a portion of the coating from the second substrate; and  
       removing the etched first substrate from the first tank, wherein the first substrate is rinsed with a rinsing fluid before being removed from the first tank.  
     
     
       2. A method for etching substrates as in  claim 1  wherein the first substrate is introduced into the first tank before the introduction of the etchant into the first tank. 
     
     
       3. A method for etching substrates as in  claim 1  wherein the second substrate is introduced into the second tank before the etchant is transferred from the first tank to the second tank. 
     
     
       4. A method for etching substrates as in  claim 1  wherein the etchant is transferred from the first tank to the second tank before removing the first substrate from the first tank. 
     
     
       5. A method for etching substrates as in  claim 1  wherein the coating comprises cadmium. 
     
     
       6. A method for etching substrates as in  claim 5  wherein the coating comprises a semiconductor coating. 
     
     
       7. A method for etching substrates as in  claim 6  wherein the substrate comprises a cadmium telluride photovoltaic solar cell module subassembly comprising a glass layer, a tin oxide coating and at least one semiconductor cadmium coating. 
     
     
       8. A method for etching substrates as in  claim 7  wherein each of the substrates, after being etched, comprises the glass layer and the tin oxide coating, with the cadmium coating being dissolved in the etchant. 
     
     
       9. A method for etching substrates as in  claim 1  wherein the etchant comprises an acidic solution. 
     
     
       10. The method of  claim 9  wherein the acidic solution comprises at least sulfuric acid. 
     
     
       11. A method for etching substrates as in  claim 1  wherein an ultrasonic vibration device is provided for aiding the etching of the coating, the ultrasonic vibration device being selectively submergible in the etchant during the etching. 
     
     
       12. A method for etching substrates as in  claim 1  wherein water is provided for rinsing the substrates after the substrates have been etched. 
     
     
       13. A method for etching substrates as in  claim 12  wherein each tank is provided with a cover having a water spraying device for spraying water over the substrates. 
     
     
       14. A method for etching substrates as in  claim 13  wherein a first plurality of substrates are provided, the first plurality of substrates include the first substrate, each of the first plurality of substrates have a coating selected from the group consisting of semiconductor coatings, metallic coatings, and mixtures thereof, a holding device being provided within the first tank for supporting each of the first plurality of substrates in a spaced apart arrangement. 
     
     
       15. A method for etching substrates as in  claim 14  wherein a rinsing device is provided which has a plurality of tines for delivering water to the first plurality of substrates, each tine having at least one aperture for discharging water, the tines being slidably movable across the first plurality of substrates. 
     
     
       16. A method for etching substrates as in  claim 1  wherein a pump is provided for transferring the etchant from the first tank to the second tank. 
     
     
       17. A method for etching substrates as in  claim 1  wherein the temperature of the etchant is maintained between about 20-60° C. during etching. 
     
     
       18. The method of  claim 1  wherein the etchant is transferred to the second tank before the etchant reaches saturation. 
     
     
       19. The method of  claim 1  further comprising rinsing the first substrate in the first tank with water before removing the first substrate from the first tank, the water forming a solution comprising water and etched materials, and transferring the solution to a third tank and separating the etched materials from the water in the third tank. 
     
     
       20. The method of  claim 19  further comprising etching additional substrates, different from the first and second substrates, in the first and second tanks with the etchant until the etchant reaches saturation, wherein the etching is taking place in one of the tanks at a time. 
     
     
       21. The method of  claim 20  further comprising transferring the etchant to the third tank after the etchant reaches saturation, the saturated etchant comprising etchant and etched materials, and separating the etched materials from the etchant in the third tank. 
     
     
       22. A method for etching a substrate, the method comprising: 
       providing a substrate having a coating selected from the group consisting of semiconductor coatings, metallic coatings, and mixtures thereof;  
       introducing the substrate into a first tank;  
       introducing an etchant capable of etching the coating from the substrate into a second tank;  
       transferring the etchant from the second tank to the first tank to etch at least a portion of the coating from the substrate within the first tank;  
       transferring the etchant from the first tank back to the second tank; and  
       removing the etched substrate from the first tank, wherein the substrate is rinsed with a rinsing fluid before being removed from the first tank.  
     
     
       23. A method for etching a substrate as in  claim 22  wherein the substrate is introduced into the first tank before transferring the etchant from the second tank to the first tank. 
     
     
       24. A method for etching a substrate as in  claim 22  wherein the etchant is transferred from the first tank back to the second tank before the substrate is removed from the first tank. 
     
     
       25. A method for etching a substrate of  claim 22  wherein the substrate is rinsed with water after the etchant is transferred from the first tank. 
     
     
       26. A method for etching a substrate of  claim 22  wherein the substrate comprises a cadmium telluride photovoltaic solar cell module subassembly comprising a glass layer, a tin oxide coating and at least one semiconductor cadmium coating. 
     
     
       27. A method for etching a substrate of  claim 22  wherein the etchant comprises an acidic solution. 
     
     
       28. A method for etching a substrate of  claim 22  wherein a second substrate having a coating selected from the group consisting of semiconductor coatings, metallic coatings, and mixtures thereof is introduced within the second tank, the second substrate being etched when the etchant is in the second tank. 
     
     
       29. The method of  claim 22  wherein the etchant is transferred to the second tank before the etchant reaches saturation. 
     
     
       30. A method for etching cadmium telluride photovoltaic solar cell module subassemblies comprising a glass layer, a tin oxide coating and at least one semiconductor cadmium coating, the method comprising: 
       providing at least a first and a second cadmium telluride photovoltaic solar cell module subassembly;  
       introducing at least the first subassembly and an etchant into a first tank to etch at least a portion of the coatings from the first substrate;  
       introducing at least the second subassembly into a second tank;  
       before the etchant in the first tank becomes saturated, transferring the etchant from the first tank to the second tank to etch at least a portion of the coatings from the second subassembly; and  
       removing the etched first subassembly from the first tank, wherein the first subassembly is rinsed with a rinsing fluid before being removed from the first tank.